Molecular Solvation Phenomena in Nanoscale Superfluids

加州大学伯克利分校的Birgitta Whaley在理论和计算化学项目的支持下，对最近的光谱实验揭示的两类新的量子溶剂化现象进行了微观理论分析，这些现象在理论上仍然无法解释。 其目的是揭示潜在的量子结构和动力学在光谱观测中所起的作用。 第一个要探索的现象是用分子仲氢的溶剂化层“包裹”分子，然后在超低温下将其嵌入氦团簇中的效果。 在氢和溶剂化包裹可能的纳米超流性的程度将被分析，沿着的量子统计和分子光谱常数之间的关系。 其次，氦溶剂引起的嵌入式分子和复合物的结构和激发的修改将被解决，重点是分子内隧穿，杂合物的结构，并在本地溶剂化环境和相关的溶剂激发平面有机分子周围的性质。 这项研究涉及大规模量子模拟方法的应用，在某些情况下的算法进步，以及使用动力学模型的模拟与理论分析相结合。在分子束扩展中产生的氦的小液体团簇正在成为一种越来越受欢迎的新介质，原子和分子可以嵌入其中并进行实验研究。 团簇作为一种新的环境，在其中研究分子的超低温性质，化学反应和溶剂化的能量。 该项目的成果预计将导致对冷量子力学溶剂中化学和物理行为的基本理解的新见解。

Birgitta Whaley of the University of California, Berkeley, is supported by the Theoretical and Computational Chemistry Program to carry out microscopic theoretical analysis of two classes of novel quantum solvation phenomena that have been revealed by recent spectroscopic experiments, which remain theoretically unexplained. The aim is to uncover the role played by the underlying quantum structure and dynamics in the spectroscopic observables. The first phenomenon to be explored concerns the effect of "wrapping" a molecule with the solvation layer of molecular para-hydrogen and then embedding this in a helium cluster at ultra-low temperatures. The extent of nanosuperfluidity possible in the hydrogen and solvation wrap will be analyzed, along with the relation between the quantum statistics of this and the molecular spectroscopic constants. Secondly, helium solvent-induced modifications of structure and excitations of embedded molecules and complexes will be addressed, focusing on intramolecular tunneling, structures of heterocomplexes, and on the nature of the local solvation environment and associated solvent excitations around planar organic molecules. This research involves application of large-scale quantum simulation methodology, algorithmic advances in some cases, and a combination of simulations with theoretical analysis using dynamical models. Small liquid clusters of helium that are produced in molecular beam expansions are becoming an increasingly popular new medium in which atoms and molecules can be embedded and studied experimentally. The clusters act as novel environments in which to examine ultra-low temperature properties of molecules, chemical reactions, and the energies of solvation. The outcomes of this project are expected to lead to new insights into the fundamental understanding of chemical and physical behavior in cold quantum mechanical solvents.